Budget

Alarm

SV/PS1 - Velleman Inc.

$9.99 - eBay

Piezo High Intensity Mini Siren Warble Alarm. Maximum of 107 dB when supplied with 12 V. However, can sound at lower intensities relative to voltage supplied; the lowest voltage is 4V according to listing.

Triggered by the Arduino when accelerometer undergoes vibrations greater then the set thresholds.